Power efficiency for transceiver architectures has become an important issue for portable handheld devices. Next generation wireless communication systems, Bluetooth, WLAN, GSM-EDGE, and the like, employ non-constant envelope modulation schemes in order to achieve high data-rates. Traditional designs of RF-modulator concepts employ vector modulator architectures which operate essentially as a single-sideband up-converter (SSB) using two digital-to-analog converters (DAC), two mixers and a linear power amplifier (PA). However, these architectures are power inefficient because they require a complete linear signal path. Further, the vector modulator concept requires a separation of the transceiver and the power amplifier on the mobile printed circuit board (PCB) in order to avoid parasitic coupling of the output signal into the VCO. Therefore the vector modulator transmitter approach has been replaced in some architectures by the polar modulator concept.
The polar modulator concept separates the modulation signal into an amplitude modulation (AM) signal and a phase modulation (PM) signal. The symbols or points used in polar modulation correspond or translate from Cartesian coordinates utilized in vector modulation concepts. The polar modulation concept provides power efficiency advantages, among others. However, the AM path can introduce distortions into the PM path, resulting in data loss, reduced bandwidth, and the like.